Pivotal Role of Mitochondrial Telomerase in Regulation of Vascular Tone and Redox Homeostasis

项目摘要 端粒酶是一种核糖核蛋白，可以对抗端粒缩短，最近我们的研究人员发现 调查小组在减少线粒体活性氧物种形成方面发挥非规范作用 (MtROS)在冠状动脉疾病(CAD)患者的冠状动脉小动脉中。我们证明了这一点 激活TERT可逆转血管内皮细胞从H_2O_2至 不，将表型恢复到在没有冠心病的受试者中观察到的表型。在这项提案中，我们的目标是调查 线粒体特异性影响端粒酶活性的作用及是否存在显性负剪接变异 βdel TERT在扩张器机制的这种表型改变中起关键作用。我们的中心假设是线粒体 DNA损伤是导致ROS产生增加的根本原因之一。MtROS已知为 促进动脉硬化和内皮功能障碍的发展，使个体易患血管 并发症。NO对mtROS的生成具有众所周知的抑制作用，并已被证明 增加端粒酶活性。核端粒酶或线粒体端粒酶活性是否与心血管疾病有关 未定义保护。我们开发了核(NucTERT)或线粒体(MitoTERTi)的新型抑制剂 端粒酶活性在区分核和线粒体端粒酶在血管调节中的作用 保护性表型。我们将确定线粒体端粒酶在这种机制变化中的作用 小鼠和人类抵抗血管中的健康(无中介)对疾病(过氧化氢中介)。 我们推测线粒体端粒酶通过防止线粒体DNA损伤起到保护作用。 正常情况下，而βdel TERT在疾病中的表达抑制了这种保护作用，并上调了 血管细胞氧化应激，并诱导NO转化为作为FMD介质的H_2O_2。这将是 通过解决两个具体目标来进行测试。 首先，我们将确定TERT的线粒体定位是否必要且足以维持 NO而不是mtH_2O_2作为人体微循环流动诱导扩张的介质。第二，我们将 探讨CAD诱导NO转化为作为FMD介体的H_2O_2的机制 线粒体功能受损涉及β-del TERT的蓄积。我们将利用现有的药理和 基因工具将导致疾病中微血管功能的恢复策略。这一新的假设 具有重要的翻译潜力，确定减缓病理变化的新治疗靶点 与微血管疾病有关。

Project Abstract Telomerase a ribo-nucleoprotein that counteracts telomere shortening has recently been shown by our investigative team to have a non-canonical role in attenuating formation of mitochondrial reactive oxygen species (mtROS) in coronary arterioles from subjects with coronary artery disease (CAD). We demonstrated that activation of TERT can reverse the mechanism of flow-induced endothelium-dependent dilation from H2O2- to NO, restoring the phenotype to one observed in subjects without CAD. In this proposal, we aim to investigate the role of mitochondrial specific effects of telomerase activity and whether the dominant negative splice variant β del TERT is critical in this phenotypic change in dilator mechanism. Our central hypothesis is that mitochondrial DNA damage is one of the underlying causes that leads to increase in ROS production. mtROS is known to promote development of arteriolosclerosis and endothelial dysfunction predisposing individuals to vascular complications. NO has a well-known inhibitory effect on mtROS generation and has also been demonstrated to increase telomerase. Whether nuclear or mitochondrial telomerase activity contributes to cardiovascular protection is not defined. We developed novel inhibitors of nuclear (nucTERT) or mitochondrial (mitoTERTi) telomerase activity to differentiate the roles of nuclear and mitochondrial telomerase in mediating vascular protective phenotypes. We will identify the role of mitochondrial telomerase in this change of mechanism from health (NO mediation) to disease (H2O2 mediation) in mouse and human resistance vessels. We hypothesize that mitochondrial telomerase plays a protective role by preventing mtDNA damage in normal conditions, while expression of β del TERT in disease suppresses this protective effect and elevates vascular cellular oxidative stress, and induces the conversion from NO to H2O2 as the mediator of FMD. This will be tested by addressing two specific aims. First, we will determine whether mitochondrial localization of TERT is necessary and sufficient to maintain NO rather than mtH2O2 as the mediator of flow-induced dilation in the human microcirculation. Second, we will investigate whether the mechanism by which CAD elicits a switch from NO to H2O2 as the mediator of FMD and impairs mitochondrial function involves accumulation of β-del TERT. We will use existing pharmacological and genetic tools that will lead to strategies for restoration of microvascular function in disease. This novel hypothesis has important translational potential, identifying new therapeutic targets for moderating the pathological changes associated with microvascular disease.